Here’s how I changed the ggplot font type in R:

1. Install the R package extrafont and load it:

install("extrafont")
library(extrafont)

2. Use this command to import your fonts to R:

font_import()

3. After the font have finished being processed, you can view your font library with the command

fonts()

4. Alter the font in your ggplot by using the command such as:

theme(text=element_text(size=11, family="Times New Roman"))